Late Carboniferous mountain-basin framework of Northeastern Qaidam area

Key words:  Northeastern Qaidam area  Late Carboniferous  mountain-basin framework  geochemistry  detrital zircon

Abstract:

The characteristics and structural attribute of the provenance of Keluke Formation clastic rocks from Shihuigou profile were studied according to the geochemistry, test data of detrital zircon and geotectonic theory. It is found that the type of late Carboniferous basin in northeastern Qaidam margin is passive margin basin. And the intermediate-acid magmatic rocks of the rock assemblage are dominant in the provenance. The basic-intermediate acidic rocks are absent, and there is no obvious sedimentary cycle. Provenance of Keluke Formation is mainly composed of antique basement. However, it also involves a certain amount of Caledonian period material, indicating the north Qaidam tectonic belt is still one of the detrital material sources. The Late Carboniferous transgression and basin subsidence are controlled by the Zongwulong late Paleozoic aulacogen in the north. And the detrital material came from the north Qaidam Caledonian orogenic belt, showing the basin-orogen pattern of "southern mountain-northern sea". The internal basin is filled with marine sedimentary. The denudation history of North Qaidam Paleozoic orogen started from ca. 430 Ma, and its existence is no later than Late Carboniferous. The arc magmatic rocks are erased in the earlier stage and the erosion of antique basement happens in the later period.